Plastic carpule and method of manufacture

Abstract

A carpule and its method of manufacture, the carpule tubular body composed of a polypropylene or similar polymer, the tubular body being sealed at one end by a seal of a thermoplastic vulcanizate (TPV) or similar polymer, the seal having been injection molded in contact with the tubular body prior to full curing of the material composing the tubular body, such that a chemical fusion bond is created between the seal and the tubular body.

1. A method of manufacturing a carpule having a tubular body, a seal end and a seal member closing said seal end of said tubular body, comprising the steps of:
 providing a mold defining a tubular body cavity; 
 injecting a first polymer into said body cavity to form said tubular body and allowing said first polymer to partially cure; 
 reconfiguring said mold to define a seal cavity such that a portion of said first polymer is exposed within said seal cavity; 
 injecting a second polymer into said seal cavity to form said seal member, wherein said second polymer contacts said first polymer while said first polymer is only partially cured; 
 allowing said first and said second polymers to fully cure. 
 
     
     
       2. The method of  claim 1 , wherein said step of providing a mold defining a tubular body cavity comprises providing a mold having a main body, an insert member and a first injection cap member, and
 wherein said step of reconfiguring said mold to define a seal cavity comprises replacing said first injection cap member with a second injection cap member. 
 
     
     
       3. The method of  claim 1 , wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is internal to said tubular body. 
     
     
       4. The method of  claim 1 , wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is external to said tubular body. 
     
     
       5. The method of  claim 1 , wherein said step of providing a mold defining a tubular body cavity comprises defining said tubular body cavity to have an internal annular shoulder and a bore, wherein the diameter of said bore is larger on the side of said internal annular shoulder facing away from said seal end, and
 wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is internal to said tubular body and such that said internal annular shoulder is exposed within said seal cavity. 
 
     
     
       6. A carpule manufactured by the method of  claim 1 . 
     
     
       7. The method of  claim 1 , further comprising the steps of choosing said first polymer from the group of polymers that cure into a rigid state and choosing said second polymer from the group of polymers that cure into an elastomeric state. 
     
     
       8. The method of  claim 7 , wherein said step of choosing said first polymer comprises choosing said first polymer from the group of polymers consisting of polypropylene and polystyrene. 
     
     
       9. The method of  claim 7 , wherein said step of choosing said second polymer comprises choosing said second polymer from the group of polymers consisting of thermoplastic vulcanizates. 
     
     
       10. A method of manufacturing a carpule having a tubular body and a seal member closing one end of said tubular body, comprising the steps of:
 providing a mold defining a tubular body cavity; 
 injecting a first polymer into said body cavity to form said tubular body and allowing said first polymer to partially cure; 
 reconfiguring said mold to define a seal cavity wherein a portion of said tubular body defines a part of said seal cavity; 
 injecting a second polymer into said seal cavity to form said seal member, wherein said second polymer contacts said portion of said tubular body while said first polymer is only partially cured; 
 allowing said first polymer to fully cure into a rigid state and said second polymer to fully cure into an elastomeric state. 
 
     
     
       11. The method of  claim 10 , wherein said step of providing a mold defining a tubular body cavity comprises providing a mold having a main body, an insert member and a first injection cap member, and
 wherein said step of reconfiguring said mold to define a seal cavity comprises replacing said first injection cap member with a second injection cap member. 
 
     
     
       12. The method of  claim 10 , wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is internal to said tubular body. 
     
     
       13. The method of  claim 10 , wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is external to said tubular body. 
     
     
       14. The method of  claim 10 , wherein said step of providing a mold defining a tubular body cavity comprises defining said tubular body cavity to have an internal annular shoulder and a bore, wherein the diameter of said bore is larger on the side of said internal annular shoulder facing away from said seal end, and
 wherein said step of reconfiguring said mold to define a seal cavity comprises defining said seal cavity such that said seal cavity is internal to said tubular body and such that said internal annular shoulder defines a portion of said seal cavity.